The need for both voice telephony services as well as data services is common. Traditionally, this may only be achieved through the use of separate services. For example, dedicated voice telephony services and dedicated data services are provided over separate and distinct networks. This is a significant disadvantage because of the high expense of maintaining and paying for such separate and distinct services, not to mention the inconvenience and inefficiency introduced because voice and data services are not integrated.
Packet-switched telecommunications networks may be based on any of a variety of technologies and protocols such as, for example, Asynchronous Transfer Mode (“ATM”), MultiProtocol Label Switching (“MPLS”), Internet Protocol (“IP”), Frame Relay (“FR”), and X.25. Packet-switched telecommunications networks have data packets, cells, frames or blocks (hereinafter “packets” or “cells”) that are either of fixed length or variable length. Although originally designed to transmit data, as opposed to voice or voice encoded data, packet-switched telecommunications networks may be used for voice communications. Some of the packet-switched technologies that may be used for voice communications include, without limitation, Voice Telephony over ATM (“VToA”), Voice over Frame-Relay (“VoFR”), Voice over Digital Subscriber Line (“VoDSL”), and Voice over IP (“VoIP”).
Focusing on VToA when compared to voice communications or voice telephony provided over traditional circuit-dedicated or circuit-switching telecommunications networks, the use of VToA, unfortunately, presents significant problems and disadvantages, especially in view of the fact that the needs of both data communications and voice communications must be met over the same network. For example, VToA does not provide advanced telephony services and features that are commonly found in traditional circuit-dedicated telecommunications networks. Similarly, advanced signaling, also commonly found in traditional circuit-dedicated telecommunications networks, is not available for VToA in the same manner that circuit-dedicated or circuit-switching telecommunications networks.
To setup and establish a Switched Virtual Circuit (“SVC”) to support VToA between a calling party and a called party, various signaling or ATM messages are used within the ATM network. This may be achieved using ATM setup and connect messages. Once ATM signaling has established an SVC, a data connection is defined and data, such as voice encoded data, may be communicated. Voice encoded data may continue to be communicated until one end of the SVC issues a release message (or any similar message that causes a disconnection). At such time, the SVC is released and voice communications ceases. Examples of traditional ATM signaling used to setup and release point-to-point and point-to-multipoint SVCs for telephony applications are illustrated in the book entitled Hands-On ATM by David E. McDysan and Darren L. Spohn, which is incorporated herein for all purposes.
In a traditional telecommunications or voice network, signaling can be in-band or out-of-band. Signaling may be used to setup and establish voice circuits, to provide Intelligent Network (“IN”) or Advanced Intelligent Network (“AIN”) services and features, and to disconnect voice circuits. In an ATM network, where an SVC is established to support VToA, signaling is achieved through the use of ATM messages, such as those used to setup and disconnect SVCs. Unfortunately, such ATM signaling does not support IN or AIN to provide the advanced telephony services and features commonly found in traditional voice telecommunications networks. This significantly reduces the attractiveness of VToA as compared to traditional voice telecommunications networks or even some other data or packet networks capable of providing voice or telephony communications services.
More particularly, a serious problem and drawback of existing VTOA is the difficulty or inability to institute advanced calling features on an ATM network-wide basis. Unfortunately, many customary and advanced voice telephony services, which are often available through traditional telecommunications networks designed to transport and support voice telephony, such as circuit-dedicated telecommunications networks, are not available or easily achieved or implemented with VTOA. For example, the capability to block calls from one or more locations in a corporation to other locations or areas, such as a specified country or countries, is a valuable service or option that is available in traditional voice telecommunications networks. To implement such a service or feature in a traditional VTOA would require that blocking information be provided in various systems and gateways and updated as needed. This is inefficient, cumbersome and expensive to carry out. As is illustrated, this type of a service is problematic to implement in traditional VTOA networks and systems. Various other valuable telecommunications services and features, which may be available in traditional telecommunications networks, suffer from the same significant disadvantage illustrated above.
In addition to the significant limitations in ATM signaling to support advanced or intelligent network telephony, the administration and maintenance of VToA systems and processes is extremely burdensome and expensive. For example, numerous private and public phone numbers, which change frequently, have to be updated and maintained in various systems and gateways. As moves, adds, changes, and deletions occur, each VToA gateway must be updated with the relevant changes. This is a critical task that is onerous and expensive to perform and fraught with potential errors.
Another serious drawback of traditional ATM network signaling is the lack of control regarding the establishment of point-to-multipoint connections. A point-to-multipoint connection may be defined as a unidirectional connection from a root node to multiple leaf nodes. Leaf nodes may be added or dropped as needed, without any automatic control or restriction on the bandwidth used or the number of leaf connections involved in such connections. As a result, point-to-multipoint connections on ATM networks are problematic and present a serious threat to the stability and performance of ATM networks.